Abstract: By use of an ion plating apparatus having an ionizing means which can be operated independently of the electric potential of a substrate, at the initial and final stages of the process of ion plating, a negative potential relative to that of a vapor source is applied to the substrate in order to facilitate the bombardment effect and at the intermediate stage of the process, the potential of the substrate is left floating while the ionization means is being driven in order to control the bombardment effect. In a preferred example, the apparatus has thermoelectron emitting filaments located near the substrate and a pair of anodes located on the side of the vapor source with respect to the substrate and on the opposite side of the substrate. This process permits producing relatively thick and adherent coatings.